You can see that the description of your repository on GitHub is displayed
inside fman. Use this to your advantage! Instead of the wordy description
"fman plugin for doing XYZ", use "Do XYZ". On top of that, it's great when
the description already explains how the plugin can be used. The above
example does this by mentioning the plugin's main keyboard shortcut
Ctr+Enter in the description.

Releases

GitHub lets you tag any version of your repository as a release. Before
fman installs a plugin, it first checks if such a release exists. If yes, it
downloads it. Otherwise, fman simply uses the latest commit.

You don't have to use releases if you don't want to. But they do have the
following advantage: When a release of your plugin exists, you can commit
potentially breaking changes to the repository. fman always installs the
release version so your users will not be affected. Once you've deemed the
accrued changes stable enough, you can draft a new release for fman to use.